Hydraulic drive for leatherworking machines



May 31, 1949. R. a. STEHLING H'YDRAULIC DRIVE FOR LEATHER WORKING MACHINES Filed March 1, 1948 2 SheetsSheet 1 d w '7 v m;

imam Ralph J. Eta/2122757 2 Sheets-Sheet 2 R. 'J. STEHLING HYDRAULIC DRIVE FOR LEATHER WORKING MACHINES Filed March 1,-1948 May 31, 1949.

wm 152711117 J flip/71mg :rvPiEkf llltll fll u I Patented May 31, 1949 HYDRAULIC DRIVE FOR LEATHERWORKING MACHINES Ralph J. Stehling, Milwaukee, Wis., assignorjso Chas. H. Stehling Company, Milwaukee, Wis., a corporation of Wisconsin Application March 1, 1948, Serial No. 12,412

2 Claims.

This invention relates to improvements in leather working machines of the type used in tanneries. Machines of this type generally have a work receiving roll or member which must be moved to and from an operative position and this invention refers particularly to an improved hydraulic drive for imparting such movement to this part of the machine.

For instance, in fleshing machines where the flesh side of the hide is brought against a revolving scraper roll, there is generally a work receiving roll over which the operator drapes the hide while this roll is in its inoperative work receiving position. With the hide thus applied the work receiving roll must be moved into its operative position to bring the flesh side of the hide against the revolving scraper roll.

Heretofore this movement has been imparted to the work receiving roll by means of a manually controlled mechanical clutch. The present invention substitutes a hydraulic drive for this mechanical clutch.

In the operation of machines of the type here involved the space between the frames and under the working rolls becomes quite sloppy. It is, therefore, an object of this invention to provide a hydraulic drive especially adapted for use with fieshing machines and other tannery machinery which is so arranged and constructed that all portions thereof lie outside the side frames.

Another prerequisite of machines of this character is that the work receiving roll or other part to be moved will be brought to and from its operative position with a smooth gradual deceleration so that the mechanism comes to rest and starts its motion without jar. This is especially true in machines where the part to be moved is a roller which is driven in its operative position and in which the drive therefor is established by the meshing of a pinion mounted on its shaft with a continuously revolving pinion on another shaft.

It is, therefore, another object of this invention to provide a hydraulic drive wherein reciprocation produced by a fluid pressure responsive motor is translated into the required movement of the member to be moved through a crank motion.

Still another object of this invention is to provide a drive of the character described which is so designed and constructed that when the member to be moved is in its operative position the crank through which such movement is effected is substantially on dead center to thereby hold the member in its operative position independently of the fluid pressure motor to thereby reduce the power requirement for the pump motor by relieving the fluid pressure motor of work during the time the member to be moved is in its operative position.

With the above and other objects in view, which will appear as the description proceeds, this invention resides in the novel construction, com bination and arrangement of parts substantially as hereinafter described and more particularly defined by the appended claims, it being understood that such changes in the precise embodiment of the hereindisclosed'invention may be made as come within the scope of the claims.

The accompanying drawings illustrate one complete example of the physical embodiment of the invention constructed according to the best mode so far devised for the practical application of the principles thereof, and in which:

Figure 1 is a perspective view of the main working elements of a fieshing machine with parts of the machine omitted and others indicated in broken lines, illustrating the application of this invention thereto;

Figure 2 is an end view of the machine showing the parts of the drive essential to an illustration of this invention and with the machine open and in position to receive work; and

Figure 3 is a view similar to Figure 2 but showing the parts in the positions they occupy when the machine is closed and the work receiving roll is in its operative position.

Referring now particularly to the accompanying drawings in which like numerals designate like parts, the numerals 5 and 6 indicate the side frames of a leather working machine which in the specific embodiment illustrated is a fleshing machine. As is customary in such machines a scraper roll 1 having a plurality of spiral blades, and a feed roll 8 are journaled in bearings carried by the side frames. These rolls are continuously driven in opposite directions by conventional drive means (not shown).

A work receiving roll 9 cooperates with the rolls 1 and 8. This roll is journaled in the upper ends of two lever arms l0 each of which is medially pivoted upon a stub shaft ll anchored in and extending from the outer face of the adjacent side frame. When the machine is open this work receiving roll 9 is spaced from the rolls 1 and 8 so that the operator can drape a hide thereon. With the hide in position on the roll 9 the levers II] are swung about their pivotal supports to close the machine, i. e. to bring the roll 9 into cooperative relation with the rolls 1 and 8 as shown in Figure 3.

During this closure of the machine long tooth gears 8' and 9 on the shafts of the rolls 8' and 9, respectively. are brought into mesh so that the roll 9 will be driven as well as the rolls 1 and 8. The rolls 8 and 9 are generally rubber covered to frictionally grip the hide and pull it across the face of the revolving scraper roll I which revolves in a direction opposite to the movement of the hide.

Swinging motion is imparted to the medially pivoted levers III by means of a hydraulic drive which includes a cylinder l2 havinga ram l3. The ram 13 reciprocates a rack M with which a pinion l5 meshes. The pinion I5 is fixed to a crankshaft I6 which extends across the machine and is journaled in bearings carried by the side frames. The ends of this crankshaft project beyond the outer faces of the side frames and except for this shaft no part of the drive mechanism lies between the side frames.

The pinion I5 is fixed to one end portion of the shaft, and between the side frame 5 and the pinion l5 the crankshaft l6 has an eccentric ll fixed thereto. The opposite end of the crankshaft has a crank arm I8 fixed thereto with its pin I9 coaxial with the eccentric.

Connecting rods 20 and 2| respectively connect the eccentric I1 and the crank pin IS with the pivotally mounted levers l0, and the various parts of the driving connection are so proportioned that when the roll 9 is swung to its closed operative position by rotary motion of the crankshaft the eccentric and crank are substantially on dead center, thus relieving the fluid pressure motor of the work required to hold the roll in its closed operative position.

In the opposite or open position of the machine the eccentric and crank may be on dead center but in this case it is not too essential as the weight of the roll 9 and its mounting structure hold it in its open position.

By virtue of the fact thatthe eccentric and crank are substantially on dead center when the roll 9 is in its closed, operative position a variable volume constant pressure hydraulic pump, indicated generally by the numeral 22, may be used to provide fluid pressure for the cylinder. This pump is equipped with means for varying the volume of its output in accordance with the load thereon. Hence, when the machine is closed, i. e. when the roll 9 is in its operative position, and the crank shaft is on dead center, the pump merely idles.

A treadle operated valve 23 and suitable pressure lines provide controlled connection of the cylinder with the pump. The valve is preferably of the ratchet actuated type wherein successive actuations of its treadle 24 advances the valve from position to position. One depression of the treadle connects one end of the cylinder with the fluid pressure source (the pump 22) to close the machine and the next depression of the treadle connects the opposite end of the cylinder with the fluid pressure source to open the machine.

From the foregoing description taken with the accompanying drawings it will be readily apparent that this invention not only provides a drive mechanism for the purpose set forth which is simple, inexpensive to produce and sufficiently rugged to withstand the hard usage to which it is subjected, but it also materially reduces the power required to operate the hydraulic pump by enabling the use of a variable volume constant pressure pump.

It should also be noted that the eccentric H and crank arm [8 counterbalance the weight of the work receiving roll '9 and its supporting arms I 0 as the roll is swung to its open position. This follows from the fact that the eccentric and crank arm are moved upwardly as the roll swings down. Such balanced relationship obviously achieves smoother operation and reduces wear upon the parts.

What I claim as my invention is:

1. In a leather working machine having spaced side frames and work performing and carrying elements including a roll extending across the machine substantially from side frame to side frame: a lever pivotally mounted on the outside of each side frame; said levers being free to swing about a common axis; means on the levers supporting the roll so that the roll may be swung back and forth by the levers to and from a work performing position; a rock shaft extending across the machine from side frame to side frame and journalled in bearings carried by the side frames which dispose the shaft parallel to the axis of swinging movement of said levers, said shaft having end portions protruding from the side frames; means for translating oscillation of said rock shaft through an arc of substantially into swinging movement of said levers to carry the roll to and from its work performing position, said means comprising a connecting rod attached at one end of each of said levers, an eccentric connection between the other end of each connecting rod and said rock shaft, one of said eccentric connections including an eccentric disc fixed to one protruding end portion of the rock shaft and a strap on the adjacent connecting rod embracing the disc, said eccentric connections travelling substantially between opposite dead center positions upon oscillation of the rock shaft to carry the roll either to or from operative position, and said eccentric having its major weight disposed at one side or the other of a vertical plane passing through the axis of the rock shaft in said dead center positions of the disc whereby the eccentric weight of the disc is utilized to swing the roll toward operative position during the latter portion of travel of the disc toward one dead center position; and means for oscillating said rock shaft through an arc of substantially 180, including a pinion fixed to one projecting end portion of the rock shaft, a

rack meshing with the pinion, and a hydraulic REFERENCES CITED The following references are of record in the file of this patent:

UNITED STATES PATENTS Number Name Date 513,601 Teal Jan. 30, 1894 1,131,756 Wayland Mar. 16, 1915 1,150,532 O'Brien Aug. 17, 1915 1,214,852 Wayland Feb. 6, 1917 1,763,058 Lewis June 10, 1930 1,908,342 Greist et al. May 9, 1933 2,054,443 Pierson Sept. 15, 1936 2,109,739 Wayland Mar. 1, 1938 2,433,352 1947 Edgar Dec. 30, 

